Tubing/casing connection for U-tube wells

ABSTRACT

A tubing/casing connection for U-tube wells. In a described embodiment, a tubular string connection system includes a first tubular string having an expanded entry guide; and a second tubular string having an end guided into the first tubular string by the entry guide.

BACKGROUND

The present invention relates generally to equipment utilized and operations performed in conjunction with a subterranean well and, in an embodiment described herein, more particularly provides a tubular string connection for U-tube wells.

It is known to drill a wellbore so that it intersects another wellbore. Examples of intersecting wellbores include U-tube wells and multilateral or branching wells. It is also known to interconnect tubular strings, such as casing, liner or tubing strings, in the intersecting wellbores.

However, prior systems for interconnecting tubular strings in intersecting wellbores have suffered from some disadvantages. For example, in these systems one tubular string is typically inserted into an interior of another tubular string. This generally requires that the inserted string have a reduced inner diameter, which restricts flow and access through the string. Another disadvantage is that it is at times difficult to align the tubular strings so that they properly engage each other.

Therefore, it may be seen that it would be beneficial to provide improved systems and methods for interconnecting tubular strings in intersecting wellbores. These systems and methods could be useful in other applications, as well.

SUMMARY

In carrying out the principles of the present invention, in accordance with an embodiment thereof, a tubular string connection system is provided which may be used to interconnect tubular strings in U-tube wells. Associated methods are also provided.

In one aspect of the invention, a tubular string connection system is provided which includes a first tubular string having an expanded entry guide. A second tubular string has an end guided into the first tubular string by the entry guide.

In another aspect of the invention, a method of connecting first and second tubular strings in a well is provided. The method includes the steps of: providing an expandable entry guide on the first tubular string; positioning the entry guide in the well, and then expanding the entry guide; and guiding the second tubular string into the first tubular string.

In yet another aspect of the invention, a well interconnection system is provided. The system includes two wellheads interconnected to each other by two tubular strings in sealed communication with each other at a subterranean tubular string connection. A wellbore junction is positioned between one of the wellheads and the tubular string connection. Another wellbore junction is positioned between the other wellhead and the tubular string connection.

In a further aspect of the invention, a method of connecting tubular strings in a well includes the steps of: providing an expandable entry guide on one of the tubular strings; positioning the tubular string in a wellbore; positioning another tubular string in another wellbore intersecting the first wellbore; and guiding the second tubular string into the first tubular string via the entry guide.

In a still further aspect of the invention, a well interconnection system is provided. The system includes first, second and third wellheads interconnected to each other substantially underground. The second, or middle, wellhead may operate as a pumping station for transferring fluid between the first and third wellheads.

These and other features, advantages, benefits and objects of the present invention will become apparent to one of ordinary skill in the art upon careful consideration of the detailed description of representative embodiments of the invention hereinbelow and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic partially cross-sectional view of a tubular string connection system and method embodying principles of the present invention;

FIG. 2 is a schematic partially cross-sectional view of the system and method of FIG. 1, in which additional steps of the method have been performed;

FIG. 3 is a schematic partially cross-sectional view of the system and method, in which still further steps of the method have been performed;

FIG. 4 is a schematic partially cross-sectional view of optional configuration and steps in the system and method;

FIG. 5 is a schematic partially cross-sectional view of further optional configuration and steps in the system and method;

FIG. 6 is a schematic partially cross-sectional view of still further optional configuration and steps in the system and method;

FIG. 7 is a schematic partially cross-sectional view of additional optional configuration and steps in the system and method;

FIG. 8 is a schematic partially cross-sectional view of another tubular string connection system and method embodying principles of the present invention;

FIG. 9 is a schematic partially cross-sectional view of a system and method for expanding an entry guide in the system and method of FIGS. 1 & 8;

FIG. 10 is a schematic view of a well interconnection system and method embodying principles of the present invention;

FIGS. 11A & B are schematic cross-sectional views of another tubular string connection system and method embodying principles of the present invention; and

FIG. 12 is a schematic view of another well interconnection system and method embodying principles of the present invention.

DETAILED DESCRIPTION

Representatively illustrated in FIG. 1 is a tubular string connection system 10 and associated method which embody principles of the present invention. In the following description of the system 10 and other apparatus and methods described herein, directional terms, such as “above”, “below”, “upper”, “lower”, etc., are used for convenience in referring to the accompanying drawings. Additionally, it is to be understood that the various embodiments of the present invention described herein may be utilized in various orientations, such as inclined, inverted, horizontal, vertical, etc., and in various configurations, without departing from the principles of the present invention.

As depicted in FIG. 1, a wellbore 12 has been drilled and a radially enlarged underreamed cavity 14 has been formed at a lower end of the wellbore. Note that it is not necessary for a cavity to be formed, or for the cavity to be positioned as shown in FIG. 1. For example, the cavity 14 could be formed in the wellbore 12 uphole from the lower end. Thus, it should be clearly understood that the invention is not limited to the specific details of the described embodiments.

A tubular string 16 is conveyed into the wellbore 12. The tubular string 16 could be a casing, liner, tubing, or other type of tubular string. At its lower end, the tubular string 16 includes an expandable entry guide 18 in an unexpanded configuration. The entry guide 18 is positioned within the cavity 14.

Referring additionally now to FIG. 2, the entry guide 18 is depicted in cross-section in its expanded configuration. The entry guide 18 is preferably expanded by applying increased pressure to the interior of the tubular string 16, thereby inflating the entry guide by applying a pressure differential across walls 20, 22 of the entry guide.

Other expanding means could be used, if desired. For example, the entry guide 18 could be mechanically swaged or drifted to force its walls 20, 22 outward. In that case, the walls 20, 22 would not need to be pressure-bearing. Another expansion method is described below in relation to FIG. 9.

In the cross-sectional view depicted in FIG. 2, it may be seen that the tubular string 16 also includes a latching profile 24 and a seal bore 26. These are shown in the tubular string 16 uphole from the entry guide 18, but they could be otherwise positioned. For example, the profile 24 and bore 26 could be formed on an inner side surface of the wall 20 of the entry guide 18, if desired.

The tubular string 16 is cemented in the wellbore 12 after expanding the entry guide 18. For this purpose, a check valve or cementing shoe 28 is provided in the outer end wall 22 of the entry guide 18. Cement 30 is flowed downwardly through the tubular string 16, and then outwardly through the check valve 28 into the wellbore 12, where it is permitted to harden.

Note that the terms “cement” and “cementing” are used herein to indicate not only the use of cementitious material, but also the use of any other hardenable material, such as epoxies, plastics, foams, etc., which may be used in an annulus between a tubular string and a wellbore to secure and/or seal the tubular string in the wellbore. In addition, it should be understood that it is not necessary for the tubular string 16 to be cemented in the wellbore 12 at all. The wellbore 12 could be left wholly or partially open hole, if desired.

It may be seen that the outer end wall 22 of the entry guide 18 presents an inclined generally conical exterior surface 32. Similarly, the side wall 20 presents an inclined generally conical interior surface 34. As described more fully below, the inclined surface 32 may be used to guide a cutting tool to cut through a center of the wall 22, and the inclined surface 34 may be used to guide another tubular string toward the seal bore 26 and latching profile 24 in the interior of the tubular string 16.

Referring additionally now to FIG. 3, the system 10 is depicted after another wellbore 36 has been drilled to intersect the wellbore 12. In this embodiment, a lower end of the wellbore 36 intersects a lower end of the wellbore 12, so that the wellbores are inline with each other at their intersection, thereby forming a U-tube well. However, the wellbores 12, 36 could intersect in other configurations, if desired.

As the wellbore 36 is being drilled to intersect the wellbore 12, a cutting tool, such as a drill bit, will eventually contact the inclined surface 32. Such contact between the cutting tool and the surface 32 will operate to guide the cutting tool toward the center of the wall 22, thereby helping to align the wellbore 36 with the other wellbore 16 and the entry guide 18 therein. As depicted in FIG. 3, the cutting tool has cut through the center of the wall 22, thereby cutting through the cementing shoe 28.

After the wellbore 36 has been drilled, another tubular string 38 is conveyed into the wellbore. At its lower end, the tubular string 38 includes a latch 40 and a seal 42. The lower end of the tubular string 38 enters the entry guide 18 from the wellbore 36 and the inclined surface 34 guides the tubular string so that it is inserted into the other tubular string 16.

The latch 40 engages the profile 24 to releasably secure the tubular strings 16, 38 to each other. The seal 42 sealingly engages the seal bore 26 to form a sealed connection between the tubular strings 16, 38. Note that, if the seal bore 26 and profile 24 were formed on the interior of the wall 20, then the sealed and secured connection between the strings 16, 38 could be made at an increased diameter which would not restrict flow or access through the connection.

Instead of the seal 42 and latch 40, the tubular string 38 could have any other types of sealing and securing devices. For example, an expandable sealing and securing device, such as the VersaFlex™ expandable liner hanger available from Enventure Global Technologies of Houston, Tex. could be used on the tubular string 38. In that case, the seal bore 26 and latching profile 24 may not be used in the tubular string 16.

Referring additionally now to FIG. 4, another embodiment of a tubular string connection system 44 is representatively illustrated. Features of the system 44 which are similar to those previously described are indicated in FIG. 4 using the same reference numbers. The system 44 differs from the system 10 at least in part in that the seal 42 is protected by an outer tubular sheath 46 while the tubular string 38 is conveyed through the wellbore 36.

While the tubular string 38 is being conveyed through the wellbore 36, the sheath 46 is maintained in position overlying the seal 42 by engagement between the latch 40 and a latching profile 48 formed within the sheath. As the lower end of the tubular string 38 enters an expanded entry guide 50, the sheath 46 eventually contacts the inclined portion of the wall 20, thereby releasing the latch 40 from the profile 48. The lower end of the tubular string 38 is then permitted to enter the tubular string 16, where the uncovered seal 42 seals against the bore 26 and the latch 40 engages the profile 24.

Note that in this embodiment the entry guide 50 is not cemented in the wellbore 12 and the entry guide does not have the outer end wall 22. The tubular strings 16, 38 could be conveyed into the wellbores 12, 36 after both of the wellbores have been drilled. The entry guide 50 could have been mechanically expanded.

Referring additionally now to FIG. 5, the system 10 is depicted while the wellbore 36 is being drilled. A series of spaced apart radioactive sources 52 are attached to the tubular string 16 in an inline array. A drill string 54 used to drill the wellbore 36 includes a cutting tool or drill bit 56 and a detector 58.

The detector 58 detects the radiation given off by the sources 52. For example, the sources 52 may emit gamma rays and the detector 58 may include a gamma ray sensor. Based on the characteristics of the detected radiation, the drill string 54 is guided toward the radioactive sources 52 and, thus, to intersect the wellbore 12.

Note that it is not necessary for there to be multiple sources 52. A single source 52 could provide a target for guiding the cutting tool 56, for example, based on the strength of the detected radiation. However, it is believed that the spaced apart array of sources 52 will provide additional characteristics (such as spatial distribution, etc.) to the radiation emitted by the sources so that increased accuracy in guiding the cutting tool 56 is obtained.

In FIG. 5, the cavity 14 is depicted formed in the wellbore 12 spaced apart from a lower portion 60 of the wellbore. As the cutting tool 56 cuts into the lower wellbore portion 60, thereby forming the intersection between the wellbores 12, 36, this lower wellbore portion will aid in aligning the cutting tool 56 so that it is inline with the wellbore 12. That is, it will be easier for the cutting tool 56 to proceed inline with the lower wellbore portion 60 than to deviate therefrom. In this case, the wellbore 12 may be left uncemented (at least, until the tubular strings 16, 38 are connected) to enhance this effect of the lower wellbore portion 60.

Referring additionally now to FIG. 6, another tubular string connection system 62 is representatively illustrated. Features of the system 62 which are similar to those previously described are indicated in FIG. 6 using the same reference numbers. The system 62 differs from the systems 10, 44 at least in part in that the outer end wall 22 of an expanded entry guide 64 is cut through from the inside out, that is, in an outward direction.

In this embodiment, a drill string 65, such as a coiled tubing string, is conveyed through the tubular string 16 after the entry guide 64 is expanded. The drill string 65 includes a cutting tool 66, such as a tapered mill, for cutting through the end wall 22. To help guide the cutting tool 66 toward the center of the wall 22, an interior surface 68 of the wall may be inclined, such as the generally conical shape depicted in FIG. 6. However, the end wall 22 may still have the exterior inclined surface 32 formed on it, for example, to guide the tubular string 38 into the entry guide 64 after the wall is cut through.

The drill string 65 could also include an underreamer 70 if, for example, it is desired to cut most, or all, of the end wall 22 away to provide a larger opening for the tubular string 38 to enter. In FIG. 7, the system 62 is depicted with an alternately configured entry guide 64, in which the inclined surface 32 is not provided on the end wall 22. Instead, the underreamer 70 is used to cut away substantially all of the end wall 22, and so the inclined surface 32 is not used.

Referring additionally now to FIG. 8, another tubular string connection system 72 is representatively illustrated. This system 72 is useful in situations where it is desired to form a connection between tubular strings 74, 76 in intersecting wellbores 78, 80. In the situation depicted in FIG. 8, the wellbore 78 has been washed out near the intersection between the wellbores 78, 80, and so it would be difficult to properly align the tubular strings 74, 76 using conventional methods.

In the system 72, the tubular string 74 includes an expandable entry guide 82 at its upper end. The entry guide 82 is positioned in the washed out section 84 of the wellbore 78, and is then expanded outward to the configuration shown in FIG. 8. Note that the entry guide 82 could be of use in other enlarged wellbore sections, whether or not they are washed out, such as intentionally enlarged wellbore sections (e.g., underreamed wellbores), etc.

The tubular string 76 is conveyed through the wellbore 80 and is deflected by a deflector 88 outwardly through a window 86. The window 86 was previously formed through a casing string 89 lining the wellbore 80 when the wellbore 78 was drilled outwardly from the wellbore 80. However, the window 86 could be formed, and/or the casing string 89 could be installed after the wellbore 78 is drilled, if desired. Furthermore, it is not necessary for the wellbore 80 to be lined with the casing 89 at all.

The tubular string 76 is deflected into the wellbore 78 and is lowered until it enters the entry guide 82. The seal 42 and latch 40 engage the seal bore 26 and profile 24 in the tubular string 74 as described above for the system 10. Note that the seal 42 may be protected by the sheath 46 while being conveyed through the wellbores 78, 8 o, as described above for the system 44. The sheath 46 would then be released when the tubular string 76 engages the entry guide 82, to uncover the seal 42 and permit it to seal against the bore 26. Alternatively, other sealing and/or securing devices, such as an expandable liner hanger, could be used in place of the seal 42 and/or latch 40.

Referring additionally now to FIG. 9, another method of expanding the entry guide 82 in the system 72 is representatively illustrated, apart from the remainder of the system shown in FIG. 8. In this method, a tubular string 90 is received in the entry guide 82. The tubular string 90 may be used to convey the tubular string 74 into the wellbore 78.

Thus, the tubular string 90 could include a latch (such as the latch 40) releasably attached to the profile 24 in the tubular string 74 while the tubular string 74 is being conveyed through the wellbore 80 and into the wellbore 78. Alternatively, the tubular string 90 could be inserted into the end of the tubular string 74 after the tubular string 74 is conveyed into the wellbore 78.

As another alternative, the tubular string 90 could be conveyed through the tubular string 74 in the branch or lateral wellbore 78 and into the entry guide 82. In the system 10 illustrated in FIG. 1, the tubular string 90 could be conveyed through the tubular string 16 in the main or parent wellbore 12 and into the entry guide 18 to expand the entry guide. Thus, the tubular string 90 can be conveyed into an expandable entry guide from any direction and in any type of wellbore in keeping with the principles of the invention.

The tubular string 90 includes an inflatable bladder or membrane 92. An interior of the membrane 92 is in communication with an interior of the tubular string 90 via openings 94 formed through a sidewall of the string. When it is desired to expand the entry guide 82, pressure is applied to the interior of the tubular string 90 to inflate the membrane 92. This applies an outwardly directed force to the interior surfaces of the entry guide 82, thereby causing it to deform outwardly and expand.

The entry guide 82 is depicted in FIG. 9 in its expanded configuration with the membrane 92 inflated therein. Note that a restraining device 96 carried on the tubular string 90 operates to restrain the open end of the entry guide 82 to a circular or cylindrical configuration. The device 96 also maintains the membrane 92 within the entry guide 82 when the membrane is inflated. The device 96 could be collapsed or retracted inwardly, if desired, when the tubular string 90 is retrieved after expanding the entry guide 82.

Referring additionally now to FIG. 10, a well interconnection system 100 is representatively illustrated from a top view thereof. The system 100 is used to interconnect two wellheads 102, 104. The wellheads 102, 104 are interconnected using principles of the invention described above.

A wellbore 106 drilled from the wellhead 102 intersects a wellbore 108 drilled from the wellhead 104. These wellbores 106, 108 may form a U-tube well. A tubular string 110 in the wellbore 106 may be connected to a tubular string 112 in the wellbore 108 using a tubular string connection system 10 as described above. Any of the other tubular string connection systems 44, 62, 72 described above could be used in place of the system 10.

A branch wellbore 114 drilled outwardly from the wellbore 106 intersects another branch wellbore 116 drilled outwardly from the wellbore 108. Yet another branch wellbore 118 drilled outwardly from the wellbore 106 intersects another branch wellbore 120 drilled outwardly from the wellbore 108.

A tubular string 122 in the wellbore 114 is connected to a tubular string 124 in the wellbore 116 using the tubular string connection system 10 (or another of the systems described above). Similarly, a tubular string 126 in the wellbore 118 is connected to a tubular string 128 in the wellbore 120.

A wellbore junction 130 interconnects the tubular strings 11 o, 126. A wellbore junction 132 interconnects the tubular strings 110, 122. A wellbore junction 134 interconnects the tubular strings 112, 128. A wellbore junction 136 interconnects the tubular strings 112, 124.

These wellbore junctions 130, 132, 134, 136 may be of the type described in U.S. patent application Ser. No. 10/725,140, filed Dec. 1, 2003, the entire disclosure of which is incorporated herein by this reference. Such wellbore junctions will permit independent control and monitoring of fluid flow between each of the branch wellbores 114, 116, 118, 120 and the respective wellbores 106, 108.

It may now be appreciated that the principles of the invention permit a wide variety of tubular string connection configurations in the system 100, thereby permitting a petroleum reservoir to be drained as desired using wellbores intersecting each other in various ways.

Note that any of the tubular strings 110, 112, 122, 124, 126, 128 can be gravel packed at any point in any of the respective wellbores 106, 108, 114, 116, 118, 120. For example, FIG. 10 depicts the tubular string 110 gravel packed about a screen 138 positioned between the tubular string connection 10 and the wellbore junction 132, the tubular string 112 gravel packed about a screen 140 positioned between the tubular string connection 10 and the wellbore junction 134, and the tubular string 126 gravel packed about a screen 142 positioned between the wellbore junction 130 and the tubular string connection 1 o.

The screens 138, 140, 142, or any of them, could be expandable. For example, the PoroFlex® expandable screen available from Enventure Global Technologies of Houston, Tex. could be used. If the screens 138, 140, 142 are used, they may not necessarily be gravel packed.

Referring additionally now to FIGS. 11A & B, another tubular string connection system 150 is representatively illustrated. The system 150 may be used in U-tube wells (such as depicted above for the system 10), or in intersecting and branch wellbores (such as depicted above for the system 72), or in any other type of well or well system, whether or not the well includes intersecting wellbores.

As depicted in FIG. 11A, the system 150 is used to connect two tubular strings 152, 154. Instead of expanding an entry guide prior to connecting the tubular strings 152, 154, in the system 150 the tubular string 152 has a reduced diameter portion 156 at an end thereof, which is inserted into the tubular string 154. A sealing element 158 is attached externally to the reduced diameter portion.

As depicted in FIG. 11B, the reduced diameter portion 156 is expanded radially outward, so that the sealing element 158 sealingly engages the interior of the tubular string 154. The sealing element 158 could be an elastomer, a non-elastomer, a material which swells upon contact with well fluids, a metal, etc., or any other type of material. The sealing element 158 could be carried internally on the tubular string 154, instead of externally on the tubular string 152. The sealing element 158 could be installed or positioned between the tubular strings 152, 154 before or after the tubular strings are engaged with each other. Contact between the tubular strings 152, 154 (e.g., when the inner tubular string is expanded) can cause sealing engagement between the tubular strings, even without use of a distinct sealing element.

The tubular string 152 could be expanded mechanically (e.g., by swaging, drifting, or other type of mechanical forming), hydraulically (e.g., by applying pressure across a sidewall of the tubular string, inflating a membrane, etc.), or by any other method, or any combination of methods.

Expansion of the reduced diameter portion 156 expands a minimum restriction or an inner dimension d of a flow passage 160 of the tubular string 152 as shown in FIG. 11A. After the expansion, the flow passage 160 preferably has a minimum restriction or inner dimension substantially equivalent to, or no less than, a minimum restriction or inner dimension D of the tubular string 154 (as shown in FIG. 11B). In this manner, the system 150 does not present a significant restriction to access or flow of fluids through the passages 160, 162, although some restriction may be present without departing from the principles of the invention.

Note that expansion of the portion 156 of the tubular string 152 also causes expansion of an end portion 164 of the tubular string 154. However, the end portion 164 could be expanded before the tubular string 152 is inserted into the tubular string 154, in which case, the end portion could be considered an entry guide on the tubular string 154. Note, also, that in any of the above-described systems 10, 44, 62, 72, 100 a tubular string (e.g., tubular strings 38, 76, 124, 112, 128) can be sealingly engaged within an entry guide (e.g., entry guides 18, 50, 64, 82) on another tubular string (e.g., tubular strings 16, 74, 122, 110, 126) to thereby reduce or prevent restrictions to access or flow through the connected tubular strings, whether or not the inserted tubular string is expanded within the entry guide.

Referring additionally now to FIG. 12, another well interconnection system 170 is representatively illustrated from a side view thereof. The system 170 is used to interconnect three wellheads 172, 174, 176. The wellheads 172, 174, 176 are interconnected using principles of the invention described above.

A wellbore 178 drilled from the wellhead 172 intersects a wellbore 180 drilled from the wellhead 174. These wellbores 178, 180 may form a U-tube well. A tubular string 182 in the wellbore 178 may be connected to a tubular string 184 in the wellbore 180 using a tubular string connection system 10 as described above. Any of the other tubular string connection systems 44, 62, 72, 150 described above could be used in place of the system 10.

A wellbore 186 drilled from the wellhead 174 intersects a wellbore 188 drilled from the wellhead 176. These wellbores 186, 188 may form a U-tube well. The wellbore 186 could be a branch of the wellbore 180, or vice versa. A tubular string 190 in the wellbore 186 may be connected to a tubular string 192 in the wellbore 188 using a tubular string connection system 10, or any of the other connection systems 44, 62, 72, 150 described above. The tubular strings 184, 190 may be joined to, or in communication with, each other at the wellhead 174 or in either of the wellbores 18 o, 186 below the wellhead.

The wellhead 174 may be used as a pumping station to transfer fluid between the tubular strings 184, 190. In this manner, fluid may be pumped substantially underground from wellhead 172 to wellhead 176. Any number of wellheads may be joined using this method to transfer fluid substantial distances underground. This may be beneficial in that sensitive surface environments may be avoided, unstable surface conditions or difficult surface topology may be avoided, the transferred fluid may be maintained at a desired temperature geothermally, etc.

Although tubular string connection systems 10, 44, 62, 72, 100, 150, 170 have been described above for use with tubular strings positioned in intersecting wellbores, the systems could also be used in a wellbore, or a section of a wellbore, that does not intersect another wellbore. For example, the intersecting wellbores 12, 36 in the systems 10, 44, 62 could instead be a single continuous wellbore. The system 72 could also be used in a continuous wellbore. In the system 100, each of the intersecting wellbores 106, 108, intersecting wellbores 114, 116, and intersecting wellbores 118, 120, or any combination of them, could be drilled as a continuous wellbore. In the system 170, each of the intersecting wellbores 178, 180 and intersecting wellbores 186, 188 could be drilled as a continuous wellbore.

Of course, a person skilled in the art would, upon a careful consideration of the above description of representative embodiments of the invention, readily appreciate that many modifications, additions, substitutions, deletions, and other changes may be made to these specific embodiments, and such changes are contemplated by the principles of the present invention. Accordingly, the foregoing detailed description is to be clearly understood as being given by way of illustration and example only, the spirit and scope of the present invention being limited solely by the appended claims and their equivalents. 

1. A tubular string connection system, comprising: a first tubular string having an expanded entry guide; and a second tubular string having an end guided into the first tubular string by the entry guide.
 2. The system of claim 1, wherein the first tubular string is positioned in a first wellbore, and the second tubular string is positioned in a second wellbore.
 3. The system of claim 1, wherein the entry guide includes at least one inclined surface for guiding the second tubular string into the first tubular string.
 4. The system of claim 3, wherein the inclined surface is an external surface on an outer end of the entry guide.
 5. The system of claim 3, wherein the inclined surface is an interior surface of the entry guide.
 6. The system of claim 1, wherein the entry guide is expanded by applying a pressure differential across a wall of the entry guide.
 7. The system of claim 1, wherein the entry guide is expanded by inflating a membrane within the entry guide.
 8. The system of claim 1, wherein an outer end wall of the expanded entry guide is cut through from an interior to an exterior of the entry guide.
 9. The system of claim 1, wherein an outer end wall of the expanded entry guide is cut through from an exterior to an interior of the entry guide.
 10. The system of claim 1, wherein the second tubular string includes a sheath protecting a seal on the second tubular string, the sheath displacing to uncover the seal when the second tubular string engages the expanded entry guide.
 11. A method of connecting first and second tubular strings in a well, the method comprising the steps of: providing an expandable entry guide on the first tubular string; positioning the entry guide in the well, and then expanding the entry guide; and guiding the second tubular string into the first tubular string.
 12. The method of claim 11, wherein the providing step further comprises providing an inclined surface on the entry guide, and wherein the guiding step further comprises using the inclined surface to guide the second tubular string into the first tubular string.
 13. The method of claim 11, wherein the guiding step further comprises releasing a protective sheath to thereby uncover a seal on the second tubular string.
 14. The method of claim 13, further comprising the step of sealingly engaging the seal within the first tubular string, thereby providing sealed communication between the first and second tubular strings.
 15. The method of claim 13, wherein the releasing step further comprises releasing the sheath from a latch carried on the second tubular string.
 16. The method of claim 15, further comprising the step of engaging the latch with a profile in the first tubular string, thereby securing the second tubular string to the first tubular string.
 17. The method of claim 11, further comprising the step of securing the second tubular string to the first tubular string.
 18. The method of claim 17, wherein the securing step further comprises engaging a profile formed within the first tubular string.
 19. The method of claim 18, wherein in the profile engaging step, the profile is formed within the entry guide.
 20. The method of claim 17, wherein the securing step further comprises expanding the second tubular string within the first tubular string.
 21. The method of claim 17, wherein the securing step further comprises engaging a latch on the second tubular string with the first tubular string.
 22. The method of claim 17, wherein the securing step further comprises engaging a latch with a profile.
 23. The method of claim 11, further comprising the step of cutting through an outer end wall of the entry guide.
 24. The method of claim 23, wherein the cutting step further comprises guiding a cutting tool using an inclined surface formed on the outer end wall.
 25. The method of claim 23, wherein the cutting step further comprises cutting inwardly through the outer end wall.
 26. The method of claim 23, wherein the cutting step further comprises cutting outwardly through the outer end wall.
 27. The method of claim 23, wherein the cutting step further comprises cutting through a check valve.
 28. The method of claim 27, further comprising the step of cementing the first tubular string in the well by flowing cement outwardly through the check valve prior to the cutting step.
 29. The method of claim 23, further comprising the step of guiding a cutting tool toward the outer end wall using at least one radioactive source attached to the first tubular string.
 30. The method of claim 29, wherein the cutting tool guiding step further comprises detecting a spaced apart series of the radioactive sources.
 31. The method of claim 29, wherein in the cutting step the first tubular string is positioned in a first wellbore, and wherein the cutting tool guiding step further comprises guiding the cutting tool through a second wellbore.
 32. The method of claim 11, wherein the positioning step further comprises positioning the first tubular string in a first wellbore, and wherein the guiding step further comprises displacing the second tubular string in a second wellbore intersecting the first wellbore.
 33. The method of claim 32, further comprising the step of guiding a cutting tool to form the second wellbore so that it intersects the first wellbore.
 34. The method of claim 33, wherein the cutting tool guiding step further comprises guiding the cutting tool toward at least one radioactive source on the first tubular string.
 35. The method of claim 33, wherein the cutting tool guiding step further comprises guiding the cutting tool toward a spaced apart array of radioactive sources on the first tubular string.
 36. The method of claim 11, wherein the guiding step further comprises displacing the second tubular string through a window.
 37. The method of claim 36, further comprising the step of forming the window in a sidewall of a third tubular string lining the second wellbore.
 38. The method of claim 11, wherein the expanding step further comprises applying a pressure differential across a wall of the entry guide.
 39. The method of claim 11, wherein the expanding step further comprises inflating a membrane within the entry guide.
 40. The method of claim 39, further comprising the step of conveying the membrane into the entry guide on a third tubular string, and wherein the inflating step further comprises applying pressure to an interior of the third tubular string.
 41. The method of claim 11, further comprising the step of sealingly engaging the first and second tubular strings with each other.
 42. The method of claim 41, wherein the sealingly engaging step further comprises attaching a seal on the first tubular string.
 43. The method of claim 41, wherein the sealingly engaging step further comprises attaching a seal on the second tubular string.
 44. The method of claim 41, wherein the sealingly engaging step further comprises expanding the second tubular string within the first tubular string.
 45. The method of claim 41, wherein the sealingly engaging step further comprises positioning a seal between the first and second tubular strings after the guiding step.
 46. The method of claim 41, wherein the sealingly engaging step further comprises swelling a sealing element between the first and second tubular strings.
 47. The method of claim 41, wherein the sealingly engaging step further comprises causing metal to metal contact between the first and second tubular strings.
 48. The method of claim 11, wherein the guiding step further comprises inserting a portion of the second tubular string into a portion of the first tubular string.
 49. The method of claim 48, further comprising the step of expanding the second tubular string portion within the first tubular string portion.
 50. The method of claim 49, wherein the second tubular string portion expanding step further comprises increasing an inner dimension of the second tubular string, thereby causing the second tubular string inner dimension to become equivalent to an inner dimension of the first tubular string.
 51. The method of claim 49, wherein the second tubular string portion expanding step further comprises increasing an inner dimension of the second tubular string, thereby causing the second tubular string inner dimension to become at least as large as an inner dimension of the first tubular string.
 52. The method of claim 49, wherein the second tubular string portion expanding step further comprises sealingly engaging the second tubular string portion with the first tubular string portion.
 53. The method of claim 48, wherein in the inserting step, the first tubular string portion is the entry guide.
 54. A well interconnection system, comprising: first and second wellheads interconnected to each other by first and second tubular strings in sealed communication with each other at a first subterranean tubular string connection; a first wellbore junction disposed between the first wellhead and the first tubular string connection; and a second wellbore junction disposed between the second wellhead and the first tubular string connection.
 55. The system of claim 54, wherein the first tubular string includes a screen.
 56. The system of claim 55, wherein the screen is gravel packed.
 57. The system of claim 55, wherein the screen is expanded in the well.
 58. The system of claim 55, wherein the screen is positioned between the first wellbore junction and the first tubular string connection.
 59. The system of claim 54, wherein the first and second wellbore junctions are interconnected to each other by third and fourth tubular strings in sealed communication with each other at a second subterranean tubular string connection.
 60. The system of claim 59, wherein the third tubular string includes a screen.
 61. The system of claim 60, wherein the screen is gravel packed.
 62. The system of claim 60, wherein the screen is expanded in the well.
 63. The system of claim 60, wherein the screen is positioned between the first wellbore junction and the second tubular string connection.
 64. A method of connecting first and second tubular strings in a well, the method comprising the steps of: providing an expandable entry guide on the first tubular string; positioning the first tubular string in a first wellbore; positioning the second tubular string in a second wellbore intersecting the first wellbore; and guiding the second tubular string into the first tubular string via the entry guide.
 65. The method of claim 64, wherein the providing step further comprises providing an inclined surface on the entry guide, and wherein the guiding step further comprises using the inclined surface to guide the second tubular string into the first tubular string.
 66. The method of claim 64, wherein the guiding step further comprises releasing a protective sheath to thereby uncover a seal on the second tubular string.
 67. The method of claim 66, further comprising the step of sealingly engaging the seal within the first tubular string, thereby providing sealed communication between the first and second tubular strings.
 68. The method of claim 66, wherein the releasing step further comprises releasing the sheath from a latch carried on the second tubular string.
 69. The method of claim 68, further comprising the step of engaging the latch with a profile in the first tubular string, thereby securing the second tubular string to the first tubular string.
 70. The method of claim 64, further comprising the step of securing the second tubular string to the first tubular string.
 71. The method of claim 70, wherein the securing step further comprises engaging a profile formed within the first tubular string.
 72. The method of claim 71, wherein in the profile engaging step, the profile is formed within the entry guide.
 73. The method of claim 70, wherein the securing step further comprises expanding the second tubular string within the first tubular string.
 74. The method of claim 70, wherein the securing step further comprises engaging a latch on the second tubular string with the first tubular string.
 75. The method of claim 70, wherein the securing step further comprises engaging a latch with a profile.
 76. The method of claim 64, further comprising the step of cutting through an outer end wall of the entry guide.
 77. The method of claim 76, wherein the cutting step further comprises guiding a cutting tool using an inclined surface formed on the outer end wall.
 78. The method of claim 76, wherein the cutting step further comprises cutting inwardly through the outer end wall.
 79. The method of claim 76, wherein the cutting step further comprises cutting outwardly through the outer end wall.
 80. The method of claim 76, wherein the cutting step further comprises cutting through a check valve.
 81. The method of claim 80, further comprising the step of cementing the first tubular string in the well by flowing cement outwardly through the check valve prior to the cutting step.
 82. The method of claim 76, further comprising the step of guiding a cutting tool toward the outer end wall using at least one radioactive source attached to the first tubular string.
 83. The method of claim 82, wherein the cutting tool guiding step further comprises detecting a spaced apart series of the radioactive sources.
 84. The method of claim 82, wherein the cutting tool guiding step further comprises guiding the cutting tool through the second wellbore.
 85. The method of claim 64, further comprising the step of guiding a cutting tool to form the second wellbore so that it intersects the first wellbore.
 86. The method of claim 85, wherein the cutting tool guiding step further comprises guiding the cutting tool toward at least one radioactive source on the first tubular string.
 87. The method of claim 85, wherein the cutting tool guiding step further comprises guiding the cutting tool toward a spaced apart array of radioactive sources on the first tubular string.
 88. The method of claim 64, wherein the guiding step further comprises displacing the second tubular string through a window.
 89. The method of claim 88, further comprising the step of forming the window in a sidewall of a third tubular string lining the second wellbore.
 90. The method of claim 64, further comprising the step of expanding the entry guide by applying a pressure differential across a wall of the entry guide.
 91. The method of claim 64, further comprising the step of expanding the entry guide by inflating a membrane within the entry guide.
 92. The method of claim 91, further comprising the step of conveying the membrane into the entry guide on a third tubular string, and wherein the inflating step further comprises applying pressure to an interior of the third tubular string.
 93. The method of claim 64, further comprising the step of sealingly engaging the first and second tubular strings with each other.
 94. The method of claim 93, wherein the sealingly engaging step further comprises attaching a seal on the first tubular string.
 95. The method of claim 93, wherein the sealingly engaging step further comprises attaching a seal on the second tubular string.
 96. The method of claim 93, wherein the sealingly engaging step further comprises expanding the second tubular string within the first tubular string.
 97. The method of claim 93, wherein the sealingly engaging step further comprises positioning a seal between the first and second tubular strings after the guiding step.
 98. The method of claim 93, wherein the sealingly engaging step further comprises swelling a sealing element between the first and second tubular strings.
 99. The method of claim 93, wherein the sealingly engaging step further comprises causing metal to metal contact between the first and second tubular strings.
 100. The method of claim 64, wherein the guiding step further comprises inserting a portion of the second tubular string into a portion of the first tubular string.
 101. The method of claim 100, further comprising the step of expanding the second tubular string portion within the first tubular string portion.
 102. The method of claim 101, wherein the second tubular string portion expanding step further comprises increasing an inner dimension of the second tubular string, thereby causing the second tubular string inner dimension to become equivalent to an inner dimension of the first tubular string.
 103. The method of claim 101, wherein the second tubular string portion expanding step further comprises increasing an inner dimension of the second tubular string, thereby causing the second tubular string inner dimension to become at least as large as an inner dimension of the first tubular string.
 104. The method of claim 101, wherein the second tubular string portion expanding step further comprises sealingly engaging the second tubular string portion with the first tubular string portion.
 105. The method of claim 100, wherein in the inserting step, the first tubular string portion is the entry guide.
 106. A well interconnection system, comprising: first, second and third wellheads interconnected to each other substantially underground.
 107. The system of claim 106, wherein the first and second wellheads are interconnected to each other by first and second tubular strings in sealed communication with each other at a first subterranean tubular string connection.
 108. The system of claim 107, wherein the second and third wellheads are interconnected to each other by third and fourth tubular strings in sealed communication with each other at a second subterranean tubular string connection.
 109. The system of claim 106, wherein the second wellhead comprises a pumping station for transferring fluid between the first and third wellheads.
 110. The system of claim 106, wherein the first and second wellheads are interconnected via first and second intersecting wellbores.
 111. The system of claim 110, wherein the second and third wellheads are interconnected via third and fourth intersecting wellbores. 